The following relates generally to wireless communication, and more specifically to redirection of a session initiation protocol (SIP) INVITE.
Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, and orthogonal frequency division multiple access (OFDMA) systems, (e.g., a Long Term Evolution (LTE) system, or a New Radio (NR) system). A wireless multiple-access communications system may include a number of base stations or access network nodes, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipment (UE).
Session initiation protocol (SIP) is a protocol used to establish a communication session (e.g., a voice call, a video call, or the like), between multiple devices, such a calling UE and a called UE. SIP defines messages that are sent between UEs, which govern establishment, termination and other essential elements of the communication session. Internet Protocol Multimedia Subsystem (IMS) is a set of specifications for offering multimedia services using the internet protocol (IP), and SIP may be used for the signaling to establish the communication session for transporting the multimedia services. To obtain IMS multimedia services, a UE registers with an IMS server. In some instances, a UE may have multiple subscriber identity module (SIM) cards. Each SIM card may correspond to a subscription for a service with a particular network provider, and the UE may separately register each SIM card with a same or different IMS server. A multi-SIM UE, however, may have issues with establishing communication sessions not contemplated by conventional systems.